Natural Resources Conservation Service s50

USDA NATURAL RESOURCES CONSERVATION SERVICE CONSERVATION PRACTICE STANDARD ARIZONA

CLOSURE OF WASTE IMPOUNDMENTS (no.) CODE 360

DEFINITION Where these impoundments are to be converted to fresh water storage and the The closure of waste impoundments (treatment original impoundment was not constructed to lagoons and waste storage ponds), that are no NRCS standards, this practice will only apply longer used for their intended purpose, in an where the investigation, as called for in environmentally safe manner. National Engineering Manual (NEM) 501.23, shows structural integrity. PURPOSE This practice may be applied as part of a CRITERIA conservation management system to support one or more of the following purposes. General Criteria Applicable to All Purposes  To protect the quality of surface water and The closure shall comply with all Federal, groundwater resources. State, and local laws, rules, and regulations.  To eliminate a safety hazard for humans All structures used to convey waste to waste and livestock impoundments shall be removed and replaced  To safeguard the public health. with compacted earth material or otherwise rendered unable to convey waste. CONDITIONS WHERE PRACTICE Liquid and slurry wastes shall be agitated and APPLIES pumped to the extent conventional pumping This practice applies to agricultural waste will allow. Clean water shall be added as impoundments that are no longer needed as a necessary to facilitate the agitation and part of a waste management system and are to pumping. The wastewater shall be utilized in be permanently closed or converted. accordance with NRCS conservation practice standard, Waste Utilization, Code 633. The

NRCS Field Office Technical Guide, Section IV NRCS-AZ

Conservation practice standards are reviewed periodically, and updated if needed. To obtain the May, 2002 current version of this standard, contact the Natural Resources Conservation Service. 360-Closure of Waste Impoundments Standard sludge remaining on the bottom and sides of downstream water resources. This may the waste treatment lagoons or waste storage include such items as silt fences, hay bale ponds may remain in place if it will not pose a barriers, temporary vegetation, and mulching. threat to the environment. If leaving the sludge in place would pose a threat, it shall be CONSIDERATIONS removed to the fullest extent practical and Reduce pumping effort to empty waste utilized in accordance with NRCS conservation impoundments where the surface is covered practice standard, Waste Utilization, Code 633. by a dense mat of floating vegetation by first Land Reclamation. Impoundments with applying herbicide to the vegetation and then embankments may be breached so that they burning the residue. Appropriate permits must will no longer impound water and excavated be obtained before burning. impoundments may be backfilled so that these Alternative methods of sludge removal may be areas may be reclaimed for other uses. Waste required where the impoundments contain impoundments that have water impounded large amounts of oyster shells, soil, or other against the embankment are considered debris. embankment structures if the depth of water is three feet or more above natural ground. Minimize the impact of odors associated with emptying and land applying wastewater and (1) Embankment Impoundments. Waste shall sludge from a waste impoundment by using an be removed from the site before the incorporation application method at a time embankment is breached. The slopes and when the humidity is low, when winds are bottom of the breach shall be stable for the soil calm, and when wind direction is away from material involved, however the side slopes populated areas. shall be no steeper than three horizontal to one vertical (3:1). Keep sludge left in place flooded to prevent its aerobic decomposition with the potential (2) Excavated Impoundments. The backfill release of nutrients to surface and ground height shall exceed the design finished grade water. by 5 percent to allow for settlement. The finished surface shall be constructed of the most clayey material available and mounded to PLANS AND SPECIFICATIONS shed rainfall runoff. Incorporate available Plans and specifications for closure of topsoil where feasible to aid establishment of abandoned waste treatment lagoons and vegetation. waste storage ponds shall be in keeping with this standard and shall describe the Conversion to Fresh Water Storage. The requirements for applying the practice to converted impoundment shall meet the achieve its intended purpose. The plans and requirements as set forth in the NRCS practice specifications shall also be consistent with the standard for the intended purpose. requirements of that standard. Safety. When sludge is not removed from a waste impoundment that is converted to fresh OPERATION AND MAINTENANCE water storage, it shall not be used for fish The proper closure of a waste treatment production. Precautions (fencing and warning lagoon or waste storage pond should require signs) shall be used to ensure that the pond is little or no operation and maintenance; not used for incompatible purposes such as however, if it is converted to another use, such swimming and livestock watering until water as a fresh water pond, operation and quality is adequate for these purposes. maintenance shall be in accordance with the Protection. All disturbed areas not returned to needs as set forth in NRCS conservation crop production shall be vegetated in practice standard for the intended purpose. accordance with seeding specifications in the Field Office Technical Guide, or other suitable measures used to control erosion and restore the esthetic value of the site. Measures shall be taken during construction to minimize site erosion and pollution of

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